Use of electrical power distribution systems, such as medium (MV) voltage power lines (cables) as a communications pathway for broadband communications is a relatively new technology. Current practice with regard to such medium voltage power line communications (PLC) have treated the power line as a simple conductor with either a specified noise distribution (such as a Gaussian noise distribution) or as an unspecified noise distribution. Noise distributions that are related to the phase of the power cycle at any instant in time have been ignored. It is known that there are noise sources associated with power distribution and in particular, medium voltage power distribution. At least some of these noise sources correlate with either the voltage or current of the 50/60 Hz power distribution waveform. For example, gap noise is the noise associated with the coupling of power line cables to one another or to devices such as line transformers, sectionalizers, reclosers and fuses. Over time, such couplings can corrode, causing regions that can act as higher resistance, and/or rectifying elements. Microarcing can occur at such couplings as the power cycle periodically approaches its peak value. Thus microarcing is a form of high frequency noise that is associated with a certain region(s) of the power cycle.
Another potential noise source for PLC systems are non-linear coupler response curves that may cause increasing signal phase distortion as power line current increases in magnitude during each power cycle.
Prior art systems do not attempt to modify the communications system during the presence of such noise that occurs during certain regions of the power cycle. Current systems use a single signal encoding method and modulation scheme for comparatively long periods of time and only occasionally modify them to adapt the changing environmental conditions. Such modifications are not related to the phase of the power cycle.